Voting has ended in Tajikistan’s referendum on amendments to the constitution.

Preliminary results of the polling will be announced on May 22, the head of the administration of Tajikistan's Central Election Commission, Abdumannon Dodozoda, told TASS.

"Two hours before the end of the voting, the voter turnout was 88.3 percent as 3.9 million Tajik citizens had already cast their votes," Dodozada said.

The amendments are expected to strengthen the grip on power of President Emomali Rahmon.

The May 22 referendum included 41 proposed amendments to the constitution.

Voters could either vote "yes" or "no" to the package. It is not possible to vote on individual amendments.

The most important proposed amendments include eliminating the term limit for Rahmon, lowering the age of eligibility to become president, and banning the creation of faith-based political parties.

The term-limit amendment would apply only to Rahmon, owing to the "leader of the nation" status parliament voted to grant him last year, which also affords him and his family permanent immunity from criminal prosecution.

Rahmon has ruled Tajikistan for close to a quarter of a century, showing what critics say is an increased disregard for religious freedoms, civil society, and political pluralism in recent years.

The referendum also asks voters to lower the presidential age limit from 35 to 30 -- a change that could position Rahmon's 29-year-old son, Rustam Emomali, for an early succession.

The referendum further proposes a ban on the formation of parties based on religion amid the ongoing trial of key members of the Islamic Renaissance Party of Tajikistan (IRPT).

The IRPT was widely viewed as moderate before the government branded it a terrorist group last year, stripping away the most significant formal opposition to the Rahmon regime.

The last referendum in Tajikistan took place in 2003 and changed the one-term limit for the president to a two-term limit.

Tajikistan's previous referendum, in 1999, approved the legalization of religious political parties. It was necessary because the peace deal that ended Tajikistan's 1992-97 civil war stipulated that members of the opposition, the bulk of whom were from the IRPT, would receive places in government.

That referendum also approved lengthening the presidential term in office from five to seven years and later, on that basis, President Rahmon declared that the first two presidential terms did not count as part of the two-term limit.